Method and materials for patterning of an amorphous, non-polymeric, organic matrix with electrically active material disposed therein

ABSTRACT

In one method of making an organic electroluminescent device, a transfer layer is solution coated on a donor substrate. The transfer layer includes an amorphous, non-polymeric, organic matrix with a light emitting material disposed in the matrix. The transfer layer is then selectively patterned on a receptor. Examples of patterning methods include laser thermal transfer or thermal head transfer. The method and associated materials can be used to form, for example, organic electroluminescent devices.

This application is a continuation of U.S. Ser. No. 09/931,598, filedAug. 16, 2001 now U.S. Pat. No. 6,699,597, now allowed, the disclosureof which is herein incorporated by reference.

BACKGROUND

Pattern-wise thermal transfer of materials from donor sheets to receptorsubstrates has been proposed for a wide variety of applications. Forexample, materials can be selectively thermally transferred to formelements useful in electronic displays and other devices. Specifically,selective thermal transfer of color filters, black matrix, spacers,polarizers, conductive layers, transistors, phosphors, and organicelectroluminescent materials have all been proposed.

SUMMARY OF THE INVENTION

The present invention is directed to materials and methods forpatterning an amorphous, non-polymeric, organic matrix with electricallyactive material disposed in the matrix, as well as the devices formedusing the materials and methods. One embodiment of the inventionincludes a method of making an organic electroluminescent device. Atransfer layer is solution coated on a donor substrate. The transferlayer includes an amorphous, non-polymeric, organic matrix with a lightemitting material disposed in the matrix. The transfer layer is thenselectively thermally transferred to a receptor. Thermal transfer caninclude laser thermal transfer or thermal head transfer.

Another embodiment is a donor sheet that includes a substrate and atransfer layer. The transfer layer includes a solution-coated,amorphous, non-polymeric, organic matrix with a light emitting materialdisposed in the matrix. This transfer layer is capable of beingselectively thermally transferred from the donor sheet to a proximallylocated receptor. Optionally, the donor sheet also includes alight-to-heat conversion layer disposed on the substrate for convertingincident imaging radiation into heat.

Yet another embodiment is a method of making a donor sheet. The methodincludes forming a transfer layer on a substrate by solution coating acoating composition on the substrate to form an amorphous,non-polymeric, organic matrix with a light emitting material disposed inthe matrix. Optionally, the method also includes forming a light-to-heatconversion layer on the substrate.

Another embodiment is an electroluminescent device that includes a firstelectrode, a second electrode, and a light emitting layer disposedbetween the first and second electrodes. The light emitting layerincludes an amorphous, non-polymeric organic matrix with a lightemitting polymer disposed in the matrix. Such devices include, forexample, single OEL devices for, for example, lighting applications andpixelated devices, such as displays, which contain multiple OEL devices.

It will be recognized that electrically active materials other thanlight emitting materials can be disposed in an amorphous, non-polymeric,organic matrix. For example, a conducting or semiconducting material canbe disposed in the amorphous, non-polymeric, organic matrix. Applicationexamples include the formation of a hole transport layer or electrontransport layer or other charge conducting layer by disposing a holetransport material or electron transport material in an amorphous,non-polymeric, organic matrix. The matrix can be formed using, forexample, any of the materials described above. This structure can beparticularly useful for conducting or semiconducting polymeric materialsto produce a layer with lower cohesive strength than the polymer itself.

In addition, these materials and methods can also be useful fornon-thermal printing and transfer methods including, for example, inkjetprinting, screen printing, and photolithographic patterning.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIG. 1 is a schematic side view of an organic electroluminescent displayconstruction;

FIG. 2 is a schematic side view of a donor sheet for transferringmaterials according to the present invention;

FIG. 3 is a schematic side view of an organic electroluminescent displayaccording to the present invention;

FIG. 4A is a schematic side view of a first embodiment of an organicelectroluminescent device;

FIG. 4B is a schematic side view of a second embodiment of an organicelectroluminescent device;

FIG. 4C is a schematic side view of a third embodiment of an organicelectroluminescent device;

FIG. 4D is a schematic side view of a fourth embodiment of an organicelectroluminescent device;

FIG. 4E is a schematic side view of a fifth embodiment of an organicelectroluminescent device; and

FIG. 4F is a schematic side view of a sixth embodiment of an organicelectroluminescent device.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

DETAILED DESCRIPTION

The present invention contemplates materials and methods for the thermalpatterning of an amorphous, non-polymeric, organic matrix with anelectrically active material disposed therein. Such methods andmaterials can be used to form devices including organic electronicdevices and displays that include electrically active organic materials,and in particular that contain light emitting polymers or other lightemitting molecules. Examples of organic electronic devices that can bemade include organic transistors, photovoltaic devices, organicelectroluminescent (OEL) devices such as organic light emitting diodes(OLEDs), and the like. In addition, these materials and methods can alsobe useful for non-thermal printing, patterning, and transfer methodsincluding, for example, inkjet printing, screen printing, andphotolithographic patterning.

The terms “active” or “electrically active”, when used to refer to alayer or material in an organic electronic device, indicate layers ormaterials that perform a function during operation of the device, forexample producing, conducting, or semiconducting a charge carrier (e.g.,electrons or holes), producing light, enhancing or tuning the electronicproperties of the device construction, and the like. The term“non-active” refers to materials or layers that, although not directlycontributing to functions as described above, may have some non-directcontribution to the assembly or fabrication or to the functionality ofan organic electronic device.

Organic electroluminescent (OEL) display or device refers toelectroluminescent displays or devices that include an organic emissivematerial, whether that emissive material includes a small molecule (SM)emitter, a SM doped polymer, a light emitting polymer (LEP), a dopedLEP, a blended LEP, or another organic emissive material whetherprovided alone or in combination with any other organic or inorganicmaterials that are functional or non-functional in the OEL display ordevices

R. H. Friend, et al. (“Electroluminescence in Conjugated Polymers”Nature, 397, 1999, 121.), incorporated herein by reference, describe onemechanism of electroluminescence as including the “injection ofelectrons from one electrode and holes from the other, the capture ofoppositely charged carriers (so-called recombination), and the radiativedecay of the excited electron-hole state (exciton) produced by thisrecombination process.”

Materials for OEL devices can be small molecule (SM) or polymeric innature. SM materials include charge transporting, charge blocking,semiconducting, and electroluminescent organic and organometalliccompounds. Generally, SM materials can be vacuum deposited or evaporatedto form thin layers in a device. In practice, multiple layers of SMs aretypically used to produce efficient OELs since a given materialgenerally does not have both the desired charge transport andelectroluminescent properties.

LEP materials are typically conjugated polymeric or oligomeric moleculesthat preferably have sufficient film-forming properties for solutionprocessing. Conventionally, LEP materials are utilized by casting asolvent solution of the LEP material on a substrate, and evaporating thesolvent, thereby leaving a polymeric film. Other methods for forming LEPfilms include ink jetting and extrusion coating. Alternatively, LEPs canbe formed in situ on a substrate by reaction of precursor species.Efficient LEP lamps have been constructed with one, two, or more organiclayers.

OELs can also be fabricated with one or more molecular glasses.Molecular glass is the term used to describe organic, low molar mass,amorphous, film-forming compounds. Hole transporting, electrontransporting, and bipolar molecular glasses are known including thosedescribed in J. V. Grazulevicius, P. Strohriegl, “Charge-TransportingPolymers and Molecular Glasses”, Handbook of Advanced Electronic andPhotonic Materials and Devices, H. S. Nalwa (ed.), 10, 2001, 233,incorporated herein by reference. The solubility of the molecularglasses can limit the ways in which multilayer electronic structures areconventionally created. For example, it may not be possible to solutioncoat a light emitting polymer layer on top of a hole transport layer ofa molecular glass if the materials of the two layers are soluble in thesame solvents. Devices have been previously formed with, for example,solution coated hole transport layers and vapor deposited emission andelectron transport layers.

As an example of device structure, FIG. 1 illustrates an OEL display ordevice 100 that includes a device layer 110 and a substrate 120. Anyother suitable display component can also be included with display 100.Optionally, additional optical elements or other devices suitable foruse with electronic displays, devices, or lamps can be provided betweendisplay 100 and viewer position 140 as indicated by optional element130.

In some embodiments like the one shown, device layer 110 includes one ormore OEL devices that emit light through the substrate toward a viewerposition 140. The viewer position 140 is used generically to indicate anintended destination for the emitted light whether it be an actual humanobserver, a screen, an optical component, an electronic device, or thelike. In other embodiments (not shown), device layer 110 is positionedbetween substrate 120 and the viewer position 140. The deviceconfiguration shown in FIG. 1 (termed “bottom emitting”) may be usedwhen substrate 120 is transmissive to light emitted by device layer 110and when a transparent conductive electrode is disposed in the devicebetween the emissive layer of the device and the substrate. The invertedconfiguration (termed “top emitting”) may be used when substrate 120does or does not transmit the light emitted by the device layer and theelectrode disposed between the substrate and the light emitting layer ofthe device does not transmit the light emitted by the device.

Device layer 110 can include one or more OEL devices arranged in anysuitable manner. For example, in lamp applications (e.g., backlights forliquid crystal display (LCD) modules), device layer 110 might constitutea single OEL device that spans an entire intended backlight area.Alternatively, in other lamp applications, device layer 110 mightconstitute a plurality of closely spaced devices that can becontemporaneously activated. For example, relatively small and closelyspaced red, green, and blue light emitters can be patterned betweencommon electrodes so that device layer 110 appears to emit white lightwhen the emitters are activated. Other arrangements for backlightapplications are also contemplated.

In direct view or other display applications, it may be desirable fordevice layer 110 to include a plurality of independently addressable OELdevices that emit the same or different colors. Each device mightrepresent a separate pixel or a separate sub-pixel of a pixilateddisplay (e.g., high resolution display), a separate segment orsub-segment of a segmented display (e.g., low information contentdisplay), or a separate icon, portion of an icon, or lamp for an icon(e.g., indicator applications).

In at least some instances, an OEL device includes a thin layer, orlayers, of one or more suitable organic materials sandwiched between acathode and an anode. When activated, electrons are injected into theorganic layer(s) from the cathode and holes are injected into theorganic layer(s) from the anode. As the injected charges migrate towardsthe oppositely charged electrodes, they may recombine to formelectron-hole pairs which are typically referred to as excitons. Theregion of the device in which the exitons are generally formed can bereferred to as the recombination zone. These excitons, or excited statespecies, can emit energy in the form of light as they decay back to aground state.

Other layers can also be present in OEL devices such as hole transportlayers, electron transport layers, hole injection layer, electroninjection layers, hole blocking layers, electron blocking layers, bufferlayers, and the like. In addition, photoluminescent materials can bepresent in the electroluminescent or other layers in OEL devices, forexample, to convert the color of light emitted by the electroluminescentmaterial to another color. These and other such layers and materials canbe used to alter or tune the electronic properties and behavior of thelayered OEL device, for example to achieve a desired current/voltageresponse, a desired device efficiency, a desired color, a desiredbrightness, and the like.

FIGS. 4A to 4F illustrate examples of different OEL deviceconfigurations. Each configuration includes a substrate 250, an anode252, and a cathode 254. The configurations of FIGS. 4C to 4F alsoinclude a hole transport layer 258 and the configurations of FIGS. 4Band 4D to 4F include an electron transport layer 260. These layersconduct holes from the anode or electrons from the cathode,respectively. Each configuration also includes a light emitting layer256 a, 256 b, 256 c that includes one or more light emitting polymers orother light emitting molecules (e.g., small molecule light emittingcompounds) disposed in an amorphous, non-polymeric, organic matrix,according to the invention. The light emitting layer 256 a includes ahole transport material, the light emitting layer 256 b includes anelectron transport material, and the light emitting layer 256 c includesboth hole transport material and electron transport material. In someembodiments, the hole transport material or electron transport materialis a material that forms the amorphous, non-polymeric, organic matrixwhich contains the light emitting polymer or other light emittingmolecules. In other embodiments, a separate matrix-forming material isused. In addition, the hole transport material or electron transportmaterial in the light emitting layer 256 a, 256 b, 256 c can be the sameas or different from the material used in the hole transport layer 258or electron transport layer 260, respectively.

The anode 252 and cathode 254 are typically formed using conductingmaterials such as metals, alloys, metallic compounds, metal oxides,conductive ceramics, conductive dispersions, and conductive polymers,including, for example, gold, platinum, palladium, aluminum, calcium,titanium, titanium nitride, indium tin oxide (ITO), fluorine tin oxide(FTO), and polyaniline. The anode 252 and the cathode 254 can be singlelayers of conducting materials or they can include multiple layers. Forexample, an anode or a cathode may include a layer of aluminum and alayer of gold, a layer of calcium and a layer of aluminum, a layer ofaluminum and a layer of lithium fluoride, or a metal layer and aconductive organic layer.

The hole transport layer 258 facilitates the injection of holes from theanode into the device and their migration towards the recombinationzone. The hole transport layer 258 can further act as a barrier for thepassage of electrons to the anode 252. The hole transport layer 258 caninclude, for example, a diamine derivative, such asN,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine (also known as TPD)or N,N′-bis(3-naphthalen-2-yl)-N,N′-bis(phenyl)benzidine (NPB), or atriarylamine derivative, such as,4,4′,4″-Tris(N,N-diphenylamino)triphenylamine (TDATA) or4,4′,4″-Tris(N-3-methylphenyl-N-phenylamino)triphenylamine (mTDATA).Other examples include copper phthalocyanine (CuPC);1,3,5-Tris(4-diphenylaminophenyl)benzenes (TDAPBs); and other compoundssuch as those described in H. Fujikawa, et al., Synthetic Metals, 91,161 (1997) and J. V. Grazulevicius, P. Strohriegl, “Charge-TransportingPolymers and Molecular Glasses”, Handbook of Advanced Electronic andPhotonic Materials and Devices, H. S. Nalwa (ed.), 10, 233-274 (2001),both of which are incorporated herein by reference.

The electron transport layer 260 facilitates the injection of electronsand their migration towards the recombination zone. The electrontransport layer 260 can further act as a barrier for the passage ofholes to the cathode 254, if desired. As an example, the electrontransport layer 260 can be formed using the organometallic compoundtris(8-hydroxyquinolato) aluminum (Alq3). Other examples of electrontransport materials include1,3-bis[5-(4-(1,1-dimethylethyl)phenyl)-1,3,4-oxadiazol-2-yl]benzene,2-(biphenyl-4-yl)-5-(4-(1,1-dimethylethyl)phenyl)-1,3,4-oxadiazole(tBuPBD) and other compounds described in C. H. Chen, et al., Macromol.Symp. 125, 1 (1997) and J. V. Grazulevicius, P. Strohriegl,“Charge-Transporting Polymers and Molecular Glasses”, Handbook ofAdvanced Electronic and Photonic Materials and Devices, H. S. Nalwa(ed.), 10, 233 (2001), both of which are incorporated herein byreference.

A number of methods have been used or tried to make OEL devices. Forexample, SM light emitting devices have been formed by sequential vapordeposition of hole transporting, emitting, and electron transportingmolecules. Although the layers are amorphous when deposited, the layerscan crystallize over time, diminishing their charge transport andemission properties. In general, it can be difficult to solution cast SMmaterials since they tend to form crystallites upon solvent drying orlater during the device lifetime.

As another example, light emitting layers based on LEP materials havebeen fabricated by solution coating a thin layer of the polymer. Thismethod may be suitable for monochromatic displays or lamps. In the caseof devices fabricated with solution casting steps, it is much moredifficult to create multilayer devices by multiple solvent castingsteps. Multilayer devices could be produced in which layers are castfrom different solvents, a first insoluble layer is created in situ anda second layer is solvent cast, a first layer is solution cast and asecond layer is vapor deposited, or one or both of the layers iscrosslinked.

Polymer dispersed small molecule devices have been fabricated bysolution casting a blend of a host polymer (e.g. polyvinylcarbazole) anda mixture of one or more small molecule dopants. In general, thesedevices require high voltages to operate and are not suitable fordisplay applications. In addition, they suffer from the samerestrictions for patterning as the LEPs.

Another method of forming devices includes the transfer of one or moretransfer layers by laser thermal patterning as described in, forexample, U.S. Pat. Nos. 6,242,152; 6,228,555; 6,228,543; 6,221,553;6,221,543; 6,214,520; 6,194,119; 6,114,088; 5,998,085; 5,725,989;5,710,097; 5,695,907; and 5,693,446, and in co-assigned U.S. patentapplication Ser. Nos. 09/853,062; 09/844,695; 09/844,100; 09/662,980;09/662,845; 09/473,114; and 09/451,984, all of which are incorporatedherein by reference. The patterning process can depend upon the physicalproperties of the transfer layer. One parameter is the cohesive, or filmstrength, of the transfer layer. During imaging, the transfer layerpreferably breaks cleanly along the line dividing imaged and unimagedregions to form the edge of a pattern. Highly conjugated polymers whichexist in extended chain conformations, such as polyphenylenevinylenes,can have high tensile strengths and elastic moduli comparable to that ofpolyaramide fibers. In practice, clean edge formation during the laserthermal imaging of light emitting polymers can be challenging. Theundesired consequence of poor edge formation is rough, torn, or raggededges on the transferred pattern.

As an alternative to or improvement on these previous methods and toaddress some of the above-described difficulties, light emittingmaterial, such as one or more light emitting polymers (LEPs) or otherlight emitting molecules, can be solution coated as part of a coatingcomposition that includes a material capable of forming an amorphous,non-polymeric, organic matrix that resists crystallization. Theamorphous nature of the matrix can, in combination with thenon-polymeric nature of the matrix, provide low cohesive strength, ascompared to typical polymer transfer layers, during transfer from adonor medium to a receptor, as described below. The amorphous nature ofthe matrix-forming material may also act to compatibilize more than oneelectrically active material (e.g. two otherwise incompatible LEPs or anLEP and a phosphorescent emitter). LEPs will be used as an example forthe description below, but it will be recognized that other lightemitting, semiconducting, hole transporting, electron transporting, orotherwise electrically active molecules could be used in place of or inaddition to one or more LEPs. In addition, laser thermal transfer willbe used as an example of a method for forming light emitting and otherlayers, however, it will be recognized that other transfer, patterning,and printing techniques can be used, such as inkjet printing, screenprinting, thermal head printing, and photolithographic patterning.

Any non-polymeric, organic material can be used as long as the materialcan be solution coated to form an amorphous matrix and will resistsubstantial crystallization during the expected lifetime of the deviceunder the expected operating and storage conditions. Examples ofsuitable materials are described in J. V. Grazulevicius, P. Strohriegl,“Charge-Transporting Polymers and Molecular Glasses”, Handbook ofAdvanced Electronic and Photonic Materials and Devices, H. S. Nalwa(ed.), 10, 233-274 (2001); Shirota, J. Mater. Chem., 10, 1, (2000);Kreger et al., Synthetic Metals, 119, 163 (2001); PCT PatentApplications Publication Nos. WO 99/21935 and WO 00/03565; and Robinsonet al., Adv. Mat., 2000, 12(22), 1701, all of which are incorporatedherein by reference. Preferably, this non-polymeric, organic materialdoes not have a substantial propensity to form or does not form astable, crystalline phase under the expected operating and storageconditions. In addition, preferably, the non-polymeric, organic materialand light emitting material are compatible or soluble in a commonsolvent or solvents and do not substantially phase separate duringsolution coating and, more preferably, do not phase separate uponremoval of the solvent(s).

In general, when the amorphous matrix is formed, the threshold forreducing cohesion in an amorphous matrix/LEP blend is the point at whichthe LEP becomes the discontinuous phase (if there are two observablephases) or the point in which the LEP chains are dissolved by theamorphous matrix (if there is a single phase). Generally, the totalamount of light emitting polymer or other light emitting molecule is nomore than 50 wt. % of the solids of a coating composition and can be 40wt. %, 25 wt. %, or less of the solids. Typically, the ratio, by weight,of the non-polymeric, organic material to light emitting material (e.g.,light emitting polymer or polymers) is at least 1:1 and typically is inthe range of 1:1 to 100:1. Generally ratios of at least 1:1, andtypically at least 2:1 or 3:1 or more, are suitable for thermal transferapplications.

In some embodiments, the non-polymeric, organic material is also a holeor electron transport material. In some of these embodiments, a hole orelectron transport layer is formed using the non-polymeric, organicmaterial and coated with or coated onto a light emitting layercontaining the same non-polymeric, organic material as an amorphousmatrix for the light emitting material.

In some embodiments, a gradient of light emitting material can be formedby depositing several layers with different concentrations of lightemitting material to achieve a desired profile. The thermal transfermethods described below can be useful in creating such structures bysequentially transferring each of the layers. In addition, layers can beformed using different light emitting materials to achieve differentcolors or to produce, for example, stacked red, green, and blue pixelswith intervening electrodes between each pixel.

If the non-polymeric, organic material is not a hole or electrontransport material, it can be desirable to include a hole or electrontransport material as part of the coating composition. Other materialsthat can be included in the coating composition include, for example,small molecule dopants (e.g. triplet emitters); other non-polymeric,organic materials; coating aids, surfactants; particulate material to,for example, reduce cohesion; dispersants; stabilizers; andphotosensitizers.

In some embodiments, the non-polymeric, organic material used to formthe amorphous matrix is also a light emitting molecule. In theseembodiments, it is preferred that the materials and operating conditionsbe selected to favor emission by the light emitting polymer instead ofthe non-polymeric, organic material which forms the amorphous matrix.For example, the non-polymeric, organic material may be capable ofemitting light in the blue region of the spectrum. In this instance, alight emitting polymer could be selected which emits in the red or greenregions of the spectrum. Selection can be based on, for example, themechanism(s) of molecular energy transfer and the bandgap of thematerials.

Examples of suitable non-polymeric, organic materials that can form anamorphous matrix when solution coated include molecules having atetrahedral core with pendant electrically active groups. Examples ofsuch molecules include tetraphenyl methanes 1, tetraphenyl silanes 2,and tetraphenyl adamantanes 3, as well as tetraphenyl germanes,tetraphenyl plumbanes, and tetraphenyl stannanes (i.e., replace Si in 2with Ge, Pb, or Sn, respectively):

Each R is independently a substituent containing one or more conjugatedfunctional groups (for example, aryl, arylene, heteroaryl,heteroarylene, alkenyl, or alkenylene) that stabilize holes (e.g. ascation radicals), electrons (e.g. as anion radicals), or act as achromophore. Each R substituent can be the same as or different from theother R substituents. When all the R substituents are the same, themolecule typically has some symmetry. When at least one of the Rsubstituents is different, the molecule has asymmetry which may furtherfacilitate the formation and retention of an amorphous matrix. In someinstances, R includes an aromatic ring that is fused to the phenyl groupto which R is attached to form, for example, a substituted orunsubstituted naphthyl or other fused ring structure. Examples andfurther descriptions of such materials can be found in, for example, PCTPatent Application Publication No. WO 00/03565 and Robinson et al., Adv.Mat., 2000, 12(22), 1701, both of which are incorporated herein byreference.

In some embodiments, the substituents R include one or more conjugatedstructures having, for example, one or more alkenyl, alkenylene, aryl,arylene (e.g., phenylene, naphthylene, or anthrylene), heteroaryl, orheteroarylene functional groups. The substituents can have extendedπ-conjugated systems which can include heteroatoms such as nitrogen andoxygen. The conjugated systems can include electron rich moieties (e.g.a triarylamine) to stabilize cation radicals (e.g. holes), electron poormoieties to stabilize anion radicals (e.g. electrons), or a HOMO-LUMO(Highest Occupied Molecular Orbital-Lowest Unoccupied Molecular Orbital)gap in the ultraviolet to visible range to act as a chromophore.Examples of suitable R groups include, but are not limited to, thefollowing:

Specific examples of suitable tetrahedral core materials includecompounds 4-6:

X is C, Si, Ge, Pb, or Sn and R₂ is H or alkyl. Compounds 5 and 6include fluorene moieties that can be chromophoric. These particularfluorenes typically have band gaps in the blue to ultraviolet range.Such materials can be useful with LEPs that emit in the red or greenregions so that emission is primarily or exclusively from the LEP.

Also among this type of compounds are spiro compounds such as compounds7-9:

where each R is independently a conjugated structure having one or morealkenyl, alkenylene, aryl, arylene (e.g., phenylene, naphthylene, oranthrylene), heteroaryl, or heteroarylene functional groups. Thesubstituents can have extended π-conjugated systems which can includeheteroatoms such as nitrogen and oxygen. The conjugated systems caninclude electron rich moieties (e.g. a triarylamine) to stabilize cationradicals (e.g. holes), electron poor moieties to stabilize anionradicals (e.g. electrons), or a HOMO-LUMO (Highest Occupied MolecularOrbital-Lowest Unoccupied Molecular Orbital) gap in the ultraviolet tovisible range to act as a chromophore.

Other materials that can be used to form amorphous, non-polymeric,organic matrices include dendrimers. Dendrimeric compounds have a coremoiety with three or more dendritic substituents extending from the coremoiety. Examples of suitable core moieties include triphenylamine,benzene, pyridine, pyrimidine, and others described in PCT PatentApplication Serial No. WO 99/21935, incorporated herein by reference.The dendritic substituents typically contain two or more aryl, arylene(e.g., phenylene), heteroaryl, heteroarylene, alkenyl, or alkenylenesubstituents. In some embodiments, the substituents can be conjugatedstructures having one or more alkenyl, alkenylene, aryl, arylene (e.g.,phenylene, naphthylene, or anthrylene), heteroaryl, or heteroarylenemoieties. The dendritic substituents can be the same or different.Examples of dendrimeric compounds include starburst compounds based on,for example, triphenylamines, such as compounds 10-16:

Each R₁ and R₂ is independently H, F, Cl, Br, I, —SH, —OH, alkyl, aryl,heteroaryl, fluoroalkyl, fluoroalkylalkoxy, alkenyl, alkoxy, amino, oralkyl-COOH. Each R₃ is independently H, F, Cl, Br, I, alkyl,fluoroalkyl, alkoxy, aryl, amino, cyano, or nitro. Each X₁ isindependently O, S, Se, NR₃, BR₃, or PR₃. The alkyl, aryl, andheteroaryl portions of any of these substituents can be substituted orunsubstituted. Each R₁, R₂, R₃, and X₁ can be the same as or differentfrom similarly labeled substituents (i.e., all R₁ substituents can bethe same as or one or more of the R₁ substituents can be different fromeach other).

Other dendrimer compounds can have an aryl or heteroaryl moiety as acore, such as compounds 17-26:

Each Ar₁ and Ar₂ is independently a substituted or unsubstituted aryl orheteroaryl, including, for example, substituted or unsubstituted phenyl,pyridine, pyrole, furan, thiophene, or one of the following structures:

Each R₁ and R₂ is independently H, F, Cl, Br, I, —SH, —OH, alkyl, aryl,heteroaryl, fluoroalkyl, fluoroalkylalkoxy, alkenyl, alkoxy, amino, oralkyl-COOH. Each R₃ is independently H, F, Cl, Br, I, alkyl,fluoroalkyl, alkoxy, aryl, amino, cyano, or nitro. Each X₁ and X₂ isindependently O, S, Se, NR₃, BR₃, or PR₃. The alkyl, aryl, andheteroaryl portions of any of these substituents can be substituted orunsubstituted. Each R₁, R₂, R₃, X₁, and X₂ can be the same as ordifferent from similarly labeled substituents (i.e., all R₁ substituentscan be the same as or one or more of the R₁ substituents can bedifferent from each other).

Other amorphous materials include, for example, compounds 27-32:

Each Ar₁ and Ar₂ is independently a substituted or unsubstituted aryl orheteroaryl, n is an integer in the range of 1 to 6, and each R₁ isindependently H, F, Cl, Br, I, —SH, —OH, alkyl, aryl, heteroaryl,fluoroalkyl, fluoroalkylalkoxy, alkenyl, alkoxy, amino, or alkyl-COOH.Each R₃ is independently H, F, Cl, Br, I, alkyl, fluoroalkyl, alkoxy,aryl, amino, cyano, or nitro. Each X, X₁, and X₂ are independently O, S,Se, NR₃, BR₃, or PR₃. The alkyl, aryl, and heteroaryl portions of any ofthese substituents can be substituted or unsubstituted. Each R₁, R₂, R₃,X, X₁, and X₂ can be the same as or different from similarly labeledsubstituents (i.e., all R₁ substituents can be the same as or one ormore of the R₁ substituents can be different from each other).

Unless otherwise indicated, the term “alkyl” includes bothstraight-chained, branched, and cyclic alkyl groups and includes bothunsubstituted and substituted alkyl groups. Unless otherwise indicated,the alkyl groups are typically C1-C20. Examples of “alkyl” as usedherein include, but are not limited to, methyl, ethyl, n-propyl,n-butyl, n-pentyl, isobutyl, and isopropyl, and the like.

Unless otherwise indicated, the term “alkylene” includes bothstraight-chained, branched, and cyclic divalent hydrocarbon radicals andincludes both unsubstituted and substituted alkenylene groups. Unlessotherwise indicated, the alkylene groups are typically C1-C20. Examplesof “alkylene” as used herein include, but are not limited to, methylene,ethylene, propylene, butylene, and isopropylene, and the like.

Unless otherwise indicated, the term “alkenyl” includes bothstraight-chained, branched, and cyclic monovalent hydrocarbon radicalshave one or more double bonds and includes both unsubstituted andsubstituted alkenyl groups. Unless otherwise indicated, the alkenylgroups are typically C2-C20. Examples of “alkenylene” as used hereininclude, but are not limited to, ethenyl, propenyl, and the like.

Unless otherwise indicated, the term “alkenylene” includes bothstraight-chained, branched, and cyclic divalent hydrocarbon radicalshave one or more double bonds and includes both unsubstituted andsubstituted alkenylene groups. Unless otherwise indicated, the alkylenegroups are typically C2-C20. Examples of “alkenylene” as used hereininclude, but are not limited to, ethene-1,2-diyl, propene-1,3-diyl, andthe like.

Unless otherwise indicated, the term “aryl” refers to monovalentunsaturated aromatic carbocyclic radicals having one to fifteen rings,such as phenyl or bipheynyl, or multiple fused rings, such as naphthylor anthryl, or combinations thereof. Examples of aryl as used hereininclude, but are not limited to, phenyl, 2-naphthyl, 1-naphthyl,biphenyl, 2-hydroxyphenyl, 2-aminophenyl, 2-methoxyphenyl and the like.

Unless otherwise indicated, the term “arylene” refers to divalentunsaturated aromatic carbocyclic radicals having one to fifteen rings,such as phenylene, or multiple fused rings, such as naphthylene oranthrylene, or combinations thereof. Examples of “arylene” as usedherein include, but are not limited to, benzene-1,2-diyl,benzene-1,3-diyl, benzene-1,4-diyl, naphthalene-1,8-diyl,anthracene-1,4-diyl, and the like.

Unless otherwise indicated, the term “heteroaryl” refers to functionalgroups containing a monovalent five- to seven-membered aromatic ringradical with one or more heteroatoms independently selected from S, O,or N. Such a heteroaryl ring may be optionally fused to one or more ofanother heterocyclic ring(s), heteroaryl ring(s), aryl ring(s),cycloalkenyl ring(s), or cycloalkyl rings. Examples of “heteroaryl” usedherein include, but are not limited to, furyl, thiophenyl, pyrrolyl,imidazolyl, pyrazolyl, triazolyl, tetrazolyl, thiazolyl, oxazolyl,isoxazolyl, oxadiazolyl, thiadiazolyl, isothiazolyl, pyridinyl,pyridazinyl, pyrazinyl, pyrimidinyl, quinolinyl, isoquinolinyl,benzofuryl, benzothiophenyl, indolyl, and indazolyl, and the like.

Unless otherwise indicated, the term “heteroarylene” refers tofunctional groups containing a divalent five- to seven-membered aromaticring radical with one or more heteroatoms independently selected from S,O, or N. Such a heteroarylene ring may be optionally fused to one ormore of another heterocyclic ring(s), heteroaryl ring(s), aryl ring(s),cycloalkenyl ring(s), or cycloalkyl rings. Examples of “heteroarylene”used herein include, but are not limited to, furan-2,5-diyl,thiophene-2,4-diyl, 1,3,4-oxadiazole-2,5-diyl,1,3,4-thiadiazole-2,5-diyl, 1,3-thiazole-2,4-diyl,1,3-thiazole-2,5-diyl, pyridine-2,4-diyl, pyridine-2,3-diyl,pyridine-2,5-diyl, pyrimidine-2,4-diyl, quinoline-2,3-diyl, and thelike.

Suitable substituents for substituted alkyl, alkylene, alkenyl,alkenylene, aryl, arylene, heteroaryl, and heteroarylene groups include,but are not limited to, alkyl, alkylene, alkoxy, aryl, arylene,heteroaryl, heteroarylene, alkenyl, alkenylene, amino, F, Cl, Br, I,—OH, —SH, cyano, nitro, —COOH, and —COO-alkyl.

It will be recognized that electrically active materials other thanlight emitting materials can be disposed in an amorphous, non-polymeric,organic matrix. For example, a conducting or semiconducting material canbe disposed in the amorphous, non-polymeric, organic matrix. Applicationexamples include the formation of a hole transport layer or electrontransport layer or other charge conducting layer by disposing a holetransport material or electron transport material in an amorphous,non-polymeric, organic matrix. The matrix can be formed using, forexample, any of the materials described above. This structure can beparticularly useful for conducting or semiconducting polymeric materialsto produce a layer with lower cohesive strength than the polymer itself.

A variety of light emitting materials including LEP and SM lightemitters can be used. Examples of classes of suitable LEP materialsinclude poly(phenylenevinylene)s (PPVs), poly-para-phenylenes (PPPs),polyfluorenes (PFs), other LEP materials now known or later developed,and co-polymers or blends thereof Suitable LEPs can also be molecularlydoped, dispersed with fluorescent dyes or other PL materials, blendedwith active or non-active materials, dispersed with active or non-activematerials, and the like. Examples of suitable LEP materials aredescribed in Kraft, et al., Angew. Chem. Int. Ed., 37, 402-428 (1998);U.S. Pat. Nos. 5,621,131; 5,708,130; 5,728,801; 5,840,217; 5,869,350;5,900,327; 5,929,194; 6,132,641; and 6,169,163; and PCT PatentApplication Publication No. 99/40655, all of which are incorporatedherein by reference.

SM materials are generally non-polymer organic or organometallicmolecular materials that can be used in OEL displays and devices asemitter materials, charge transport materials, as dopants in emitterlayers (e.g., to control the emitted color) or charge transport layers,and the like. Commonly used SM materials include metal chelatecompounds, such as tris(8-hydroxyquinoline) aluminum (Alq3), andN,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD). Other SMmaterials are disclosed in, for example, C. H. Chen, et al., Macromol.Symp. 125, 1 (1997), Japanese Laid Open Patent Application 2000-195673,U.S. Pat. Nos. 6,030,715, 6,150,043, and 6,242,115 and, PCT PatentApplications Publication Nos. WO 00/18851 (divalent lanthanide metalcomplexes), WO 00/70655 (cyclometallated iridium compounds and others),and WO 98/55561, all of which are incorporated herein by reference.

Referring back to FIG. 1, device layer 110 is disposed on substrate 120.Substrate 120 can be any substrate suitable for OEL device and displayapplications. For example, substrate 120 can comprise glass, clearplastic, or other suitable material(s) that are substantiallytransparent to visible light. Substrate 120 can also be opaque tovisible light, for example stainless steel, crystalline silicon,poly-silicon, or the like. Because some materials in OEL devices can beparticularly susceptible to damage due to exposure to oxygen or water,substrate 120 preferably provides an adequate environmental barrier, oris supplied with one or more layers, coatings, or laminates that providean adequate environmental barrier.

Substrate 120 can also include any number of devices or componentssuitable in OEL devices and displays such as transistor arrays and otherelectronic devices; color filters, polarizers, wave plates, diffusers,and other optical devices; insulators, barrier ribs, black matrix, maskwork and other such components; and the like. Generally, one or moreelectrodes will be coated, deposited, patterned, or otherwise disposedon substrate 120 before forming the remaining layer or layers of the OELdevice or devices of the device layer 110. When a light transmissivesubstrate 120 is used and the OEL device or devices are bottom emitting,the electrode or electrodes that are disposed between the substrate 120and the emissive material(s) are preferably substantially transparent tolight, for example transparent conductive electrodes such as indium tinoxide (ITO) or any of a number of other transparent conductive oxides.

Element 130 can be any element or combination of elements suitable foruse with OEL display or device 100. For example, element 130 can be anLCD module when device 100 is a backlight. One or more polarizers orother elements can be provided between the LCD module and the backlightdevice 100, for instance an absorbing or reflective clean-up polarizer.Alternatively, when device 100 is itself an information display, element130 can include one or more of polarizers, wave plates, touch panels,antireflective coatings, anti-smudge coatings, projection screens,brightness enhancement films, or other optical components, coatings,user interface devices, or the like.

Organic electronic devices containing materials for light emission canbe made at least in part by selective thermal transfer of light emittingmaterial from a thermal transfer donor sheet to a desired receptorsubstrate. For example, light emitting polymer displays and lamps can bemade coating an LEP and a non-polymeric, organic material capable offorming an amorphous matrix on a donor sheet and then selectivelytransferring the LEP layer alone or along with other device layers ormaterials to the display substrate.

Selective thermal transfer of layers containing light emitting materialsfor organic electronic devices can be performed using a thermal transferdonor. FIG. 2 shows an example of a thermal transfer donor 200 suitablefor use in the present invention. Donor element 200 includes a basesubstrate 210, an optional underlayer 212, an optional light-to-heatconversion layer (LTHC layer) 214, an optional interlayer 216, and atransfer layer 218 that comprises an oriented or orientable emissivematerial or functional alignment layer. Each of these elements aredescribed in more detail in the discussion that follows. Other layerscan also be present. Examples of suitable donors or layers of donors aredisclosed in U.S. Pat. Nos. 6,242,152; 6,228,555; 6,228,543; 6,221,553;6,221,543; 6,214,520; 6,194,119; 6,114,088; 5,998,085; 5,725,989;5,710,097; 5,695,907; and 5,693,446, and in co-assigned U.S. patentapplication Ser. Nos. 09/853,062; 09/844,695; 09/844,100; 09/662,980;09/662,845; 09/473,114; and 09/451,984, all of which are incorporatedherein by reference.

In processes of the present invention, emissive organic materials,including LEPs or other materials, can be selectively transferred fromthe transfer layer of a donor sheet to a receptor substrate by placingthe transfer layer of the donor element adjacent to the receptor andselectively heating the donor element. Illustratively, the donor elementcan be selectively heated by irradiating the donor element with imagingradiation that can be absorbed by light-to-heat converter materialdisposed in the donor, often in a separate LTHC layer, and convertedinto heat. In these cases, the donor can be exposed to imaging radiationthrough the donor substrate, through the receptor, or both. Theradiation can include one or more wavelengths, including visible light,infrared radiation, or ultraviolet radiation, for example from a laser,lamp, or other such radiation source. Other selective heating methodscan also be used, such as using a thermal print head or using a thermalhot stamp (e.g., a patterned thermal hot stamp such as a heated siliconestamp that has a relief pattern that can be used to selectively heat adonor). Material from the thermal transfer layer can be selectivelytransferred to a receptor in this manner to imagewise form patterns ofthe transferred material on the receptor. In many instances, thermaltransfer using light from, for example, a lamp or laser, to patternwiseexpose the donor can be advantageous because of the accuracy andprecision that can often be achieved. The size and shape of thetransferred pattern (e.g., a line, circle, square, or other shape) canbe controlled by, for example, selecting the size of the light beam, theexposure pattern of the light beam, the duration of directed beamcontact with the donor sheet, or the materials of the donor sheet. Thetransferred pattern can also be controlled by irradiating the donorelement through a mask.

As mentioned, a thermal print head or other heating element (patternedor otherwise) can also be used to selectively heat the donor elementdirectly, thereby pattern-wise transferring portions of the transferlayer. In such cases, the light-to-heat converter material in the donorsheet is optional. Thermal print heads or other heating elements may beparticularly suited for making lower resolution patterns of material orfor patterning elements whose placement need not be preciselycontrolled.

Transfer layers can also be transferred from donor sheets withoutselectively transferring the transfer layer. For example, a transferlayer can be formed on a donor substrate that, in essence, acts as atemporary liner that can be released after the transfer layer iscontacted to a receptor substrate, typically with the application ofheat or pressure. Such a method, referred to as lamination transfer, canbe used to transfer the entire transfer layer, or a large portionthereof, to the receptor.

The mode of thermal mass transfer can vary depending on the type ofselective heating employed, the type of irradiation if used to exposethe donor, the type of materials and properties of the optional LTHClayer, the type of materials in the transfer layer, the overallconstruction of the donor, the type of receptor substrate, and the like.Without wishing to be bound by any theory, transfer generally occurs viaone or more mechanisms, one or more of which may be emphasized orde-emphasized during selective transfer depending on imaging conditions,donor constructions, and so forth. One mechanism of thermal transferincludes thermal melt-stick transfer whereby localized heating at theinterface between the thermal transfer layer and the rest of the donorelement can lower the adhesion of the thermal transfer layer to thedonor in selected locations. Selected portions of the thermal transferlayer can adhere to the receptor more strongly than to the donor so thatwhen the donor element is removed, the selected portions of the transferlayer remain on the receptor. Another mechanism of thermal transferincludes ablative transfer whereby localized heating can be used toablate portions of the transfer layer off of the donor element, therebydirecting ablated material toward the receptor. Yet another mechanism ofthermal transfer includes sublimation whereby material dispersed in thetransfer layer can be sublimated by heat generated in the donor element.A portion of the sublimated material can condense on the receptor. Thepresent invention contemplates transfer modes that include one or moreof these and other mechanisms whereby selective heating of a donor sheetcan be used to cause the transfer of materials from a transfer layer toreceptor surface.

A variety of radiation-emitting sources can be used to heat donorsheets. For analog techniques (e.g., exposure through a mask),high-powered light sources (e.g., xenon flash lamps and lasers) areuseful. For digital imaging techniques, infrared, visible, andultraviolet lasers are particularly useful. Suitable lasers include, forexample, high power (≧100 mW) single mode laser diodes, fiber-coupledlaser diodes, and diode-pumped solid state lasers (e.g., Nd:YAG andNd:YLF). Laser exposure dwell times can vary widely from, for example, afew hundredths of microseconds to tens of microseconds or more, andlaser fluences can be in the range from, for example, about 0.01 toabout 5 J/cm² or more. Other radiation sources and irradiationconditions can be suitable based on, among other things, the donorelement construction, the transfer layer material, the mode of thermalmass transfer, and other such factors.

When high spot placement accuracy is desired (e.g., when patterningelements for high information content displays and other suchapplications) over large substrate areas, a laser can be particularlyuseful as the radiation source. Laser sources are also compatible withboth large rigid substrates (e.g., 1 m×1 m×1.1 mm glass) and continuousor sheeted film substrates (e.g., 100 μm thick polyimide sheets).

During imaging, the donor sheet can be brought into intimate contactwith a receptor (as might typically be the case for thermal melt-sticktransfer mechanisms) or the donor sheet can be spaced some distance fromthe receptor (as can be the case for ablative transfer mechanisms ormaterial sublimation transfer mechanisms). In at least some instances,pressure or vacuum can be used to hold the donor sheet in intimatecontact with the receptor. In some instances, a mask can be placedbetween the donor sheet and the receptor. Such a mask can be removableor can remain on the receptor after transfer. If a light-to-heatconverter material is present in the donor, radiation source can then beused to heat the LTHC layer (or other layer(s) containing radiationabsorber) in an imagewise fashion (e.g., digitally or by analog exposurethrough a mask) to perform imagewise transfer or patterning of thetransfer layer from the donor sheet to the receptor.

Typically, selected portions of the transfer layer are transferred tothe receptor without transferring significant portions of the otherlayers of the donor sheet, such as the optional interlayer or LTHClayer. The presence of the optional interlayer may eliminate or reducethe transfer of material from an LTHC layer to the receptor or reducedistortion in the transferred portion of the transfer layer. Preferably,under imaging conditions, the adhesion of the optional interlayer to theLTHC layer is greater than the adhesion of the interlayer to thetransfer layer. The interlayer can be transmissive, reflective, orabsorptive to imaging radiation, and can be used to attenuate orotherwise control the level of imaging radiation transmitted through thedonor or to manage temperatures in the donor, for example to reducethermal or radiation-based damage to the transfer layer during imaging.Multiple interlayers can be present.

Large donor sheets can be used, including donor sheets that have lengthand width dimensions of a meter or more. In operation, a laser can berastered or otherwise moved across the large donor sheet, the laserbeing selectively operated to illuminate portions of the donor sheetaccording to a desired pattern. Alternatively, the laser may bestationary and the donor sheet or receptor substrate moved beneath thelaser.

In some instances, it may be necessary, desirable, or convenient tosequentially use two or more different donor sheets to form electronicdevices on a receptor. For example, multiple layer devices can be formedby transferring separate layers or separate stacks of layers fromdifferent donor sheets. Multilayer stacks can also be transferred as asingle transfer unit from a single donor element. For example, a holetransport layer and a LEP layer can be co-transferred from a singledonor. As another example, a semiconductive polymer and an emissivelayer can be co-transferred from a single donor. Multiple donor sheetscan also be used to form separate components in the same layer on thereceptor. For example, three different donors that each have a transferlayer comprising a LEP capable of emitting a different color (forexample, red, green, and blue) can be used to form RGB sub-pixel OELdevices for a full color polarized light emitting electronic display. Asanother example, a conductive or semiconductive polymer can be patternedvia thermal transfer from one donor, followed by selective thermaltransfer of emissive layers from one or more other donors to form aplurality of OEL devices in a display. As still another example, layersfor organic transistors can be patterned by selective thermal transferof electrically active organic materials (oriented or not), followed byselective thermal transfer patterning of one or more pixel or sub-pixelelements such as color filters, emissive layers, charge transportlayers, electrode layers, and the like.

Materials from separate donor sheets can be transferred adjacent toother materials on a receptor to form adjacent devices, portions ofadjacent devices, or different portions of the same device.Alternatively, materials from separate donor sheets can be transferreddirectly on top of, or in partial overlying registration with, otherlayers or materials previously patterned onto the receptor by thermaltransfer or some other method (e.g., photolithography, depositionthrough a shadow mask, etc.). A variety of other combinations of two ormore donor sheets can be used to form a device, each donor sheet formingone or more portions of the device. It will be understood that otherportions of these devices, or other devices on the receptor, may beformed in whole or in part by any suitable process includingphotolithographic processes, ink jet processes, and various otherprinting or mask-based processes, whether conventionally used or newlydeveloped.

Referring back to FIG. 2, various layers of the donor sheet 200 will nowbe described.

The donor substrate 210 can be a polymer film. One suitable type ofpolymer film is a polyester film, for example, polyethyleneterephthalate (PET) or polyethylene naphthalate (PEN) films. However,other films with sufficient optical properties, including hightransmission of light at a particular wavelength, or sufficientmechanical and thermal stability properties, depending on the particularapplication, can be used. The donor substrate, in at least someinstances, is flat so that uniform coatings can be formed thereon. Thedonor substrate is also typically selected from materials that remainstable despite heating of one or more layers of the donor. However, asdescribed below, the inclusion of an underlayer between the substrateand an LTHC layer can be used to insulate the substrate from heatgenerated in the LTHC layer during imaging. The typical thickness of thedonor substrate ranges from 0.025 to 0.15 mm, preferably 0.05 to 0.1 mm,although thicker or thinner donor substrates may be used.

The materials used to form the donor substrate and an optional adjacentunderlayer can be selected to improve adhesion between the donorsubstrate and the underlayer, to control heat transport between thesubstrate and the underlayer, to control imaging radiation transport tothe LTHC layer, to reduce imaging defects and the like. An optionalpriming layer can be used to increase uniformity during the coating ofsubsequent layers onto the substrate and also increase the bondingstrength between the donor substrate and adjacent layers.

An optional underlayer 212 may be coated or otherwise disposed between adonor substrate and the LTHC layer, for example to control heat flowbetween the substrate and the LTHC layer during imaging or to providemechanical stability to the donor element for storage, handling, donorprocessing, or imaging. Examples of suitable underlayers and methods ofproviding underlayers are disclosed in co-assigned U.S. patentapplication Ser. No. 09/743,114, incorporated herein by reference.

The underlayer can include materials that impart desired mechanical orthermal properties to the donor element. For example, the underlayer caninclude materials that exhibit a low specific heat×density or lowthermal conductivity relative to the donor substrate. Such an underlayermay be used to increase heat flow to the transfer layer, for example toimprove the imaging sensitivity of the donor.

The underlayer may also include materials for their mechanicalproperties or for adhesion between the substrate and the LTHC. Using anunderlayer that improves adhesion between the substrate and the LTHClayer may result in less distortion in the transferred image. As anexample, in some cases an underlayer can be used that reduces oreliminates delamination or separation of the LTHC layer, for example,that might otherwise occur during imaging of the donor media. This canreduce the amount of physical distortion exhibited by transferredportions of the transfer layer. In other cases, however it may bedesirable to employ underlayers that promote at least some degree ofseparation between or among layers during imaging, for example toproduce an air gap between layers during imaging that can provide athermal insulating function. Separation during imaging may also providea channel for the release of gases that may be generated by heating ofthe LTHC layer during imaging. Providing such a channel may lead tofewer imaging defects.

The underlayer may be substantially transparent at the imagingwavelength, or may also be at least partially absorptive or reflectiveof imaging radiation. Attenuation or reflection of imaging radiation bythe underlayer may be used to control heat generation during imaging.

Referring again to FIG. 2, an LTHC layer 214 can be included in donorsheets of the present invention to couple irradiation energy into thedonor sheet. The LTHC layer preferably includes a radiation absorberthat absorbs incident radiation (e.g., laser light) and converts atleast a portion of the incident radiation into heat to enable transferof the transfer layer from the donor sheet to the receptor.

Generally, the radiation absorber(s) in the LTHC layer absorb light inthe infrared, visible, or ultraviolet regions of the electromagneticspectrum and convert the absorbed radiation into heat. The radiationabsorber(s) are typically highly absorptive of the selected imagingradiation, providing an LTHC layer with an optical density at thewavelength of the imaging radiation in the range of about 0.2 to 3 orhigher. Optical density of a layer is the absolute value of thelogarithm (base 10) of the ratio of the intensity of light transmittedthrough the layer to the intensity of light incident on the layer.

Radiation absorber material can be uniformly disposed throughout theLTHC layer or can be non-homogeneously distributed. For example, asdescribed in co-assigned U.S. patent application Ser. No. 09/474,002,non-homogeneous LTHC layers can be used to control temperature profilesin donor elements. This can give rise to donor sheets that have improvedtransfer properties (e.g., better fidelity between the intended transferpatterns and actual transfer patterns).

Suitable radiation absorbing materials can include, for example, dyes(e.g., visible dyes, ultraviolet dyes, infrared dyes, fluorescent dyes,and radiation-polarizing dyes), pigments, metals, metal compounds, metalfilms, and other suitable absorbing materials. Examples of suitableradiation absorbers includes carbon black, metal oxides, and metalsulfides. One example of a suitable LTHC layer can include a pigment,such as carbon black, and a binder, such as an organic polymer. Anothersuitable LTHC layer includes metal or metal/metal oxide formed as a thinfilm, for example, black aluminum (i.e., a partially oxidized aluminumhaving a black visual appearance). Metallic and metal compound films maybe formed by techniques, such as, for example, sputtering andevaporative deposition. Particulate coatings may be formed using abinder and any suitable dry or wet coating techniques. LTHC layers canalso be formed by combining two or more LTHC layers containing similaror dissimilar materials. For example, an LTHC layer can be formed byvapor depositing a thin layer of black aluminum over a coating thatcontains carbon black disposed in a binder.

Dyes suitable for use as radiation absorbers in a LTHC layer may bepresent in particulate form, dissolved in a binder material, or at leastpartially dispersed in a binder material. When dispersed particulateradiation absorbers are used, the particle size can be, at least in someinstances, about 10 μm or less, and may be about 1 μm or less. Suitabledyes include those dyes that absorb in the IR region of the spectrum. Aspecific dye may be chosen based on factors such as, solubility in, andcompatibility with, a specific binder or coating solvent, as well as thewavelength range of absorption.

Pigmentary materials may also be used in the LTHC layer as radiationabsorbers. Examples of suitable pigments include carbon black andgraphite, as well as phthalocyanines, nickel dithiolenes, and otherpigments described in U.S. Pat. Nos. 5,166,024 and 5,351,617.Additionally, black azo pigments based on copper or chromium complexesof, for example, pyrazolone yellow, dianisidine red, and nickel azoyellow can be useful. Inorganic pigments can also be used, including,for example, oxides and sulfides of metals such as aluminum, bismuth,tin, indium, zinc, titanium, chromium, molybdenum, tungsten, cobalt,iridium, nickel, palladium, platinum, copper, silver, gold, zirconium,iron, lead, and tellurium. Metal borides, carbides, nitrides,carbonitrides, bronze-structured oxides, and oxides structurally relatedto the bronze family (e.g., W_(2.9)) may also be used.

Metal radiation absorbers may be used, either in the form of particles,as described for instance in U.S. Pat. No. 4,252,671, or as films, asdisclosed in U.S. Pat. No. 5,256,506. Suitable metals include, forexample, aluminum, bismuth, tin, indium, tellurium and zinc.

Suitable binders for use in the LTHC layer include film-formingpolymers, such as, for example, phenolic resins (e.g., novolak andresole resins), polyvinyl butyral resins, polyvinyl acetates, polyvinylacetals, polyvinylidene chlorides, polyacrylates, cellulosic ethers andesters, nitrocelluloses, and polycarbonates. Suitable binders mayinclude monomers, oligomers, or polymers that have been, or can be,polymerized or crosslinked. Additives such as photoinitiators may alsobe included to facilitate crosslinking of the LTHC binder. In someembodiments, the binder is primarily formed using a coating ofcrosslinkable monomers or oligomers with optional polymer.

The inclusion of a thermoplastic resin (e.g., polymer) may improve, inat least some instances, the performance (e.g., transfer properties orcoatability) of the LTHC layer. It is thought that a thermoplastic resinmay improve the adhesion of the LTHC layer to the donor substrate. Inone embodiment, the binder includes 25 to 50 wt. % (excluding thesolvent when calculating weight percent) thermoplastic resin, and,preferably, 30 to 45 wt. % thermoplastic resin, although lower amountsof thermoplastic resin may be used (e.g., 1 to 15 wt. %). Thethermoplastic resin is typically chosen to be compatible (i.e., form aone-phase combination) with the other materials of the binder. In atleast some embodiments, a thermoplastic resin that has a solubilityparameter in the range of 9 to 13 (cal/cm³)^(1/2), preferably, 9.5 to 12(cal/cm³)^(1/2), is chosen for the binder. Examples of suitablethermoplastic resins include polyacrylics, styrene-acrylic polymers andresins, and polyvinyl butyral.

Conventional coating aids, such as surfactants and dispersing agents,may be added to facilitate the coating process. The LTHC layer may becoated onto the donor substrate using a variety of coating methods knownin the art. A polymeric or organic LTHC layer can be coated, in at leastsome instances, to a thickness of 0.05 μm to 20 μm, preferably, 0.5 μmto 10 μm, and, more preferably, 1 μm to 7 μm. An inorganic LTHC layercan be coated, in at least some instances, to a thickness in the rangeof 0.0005 to 10 μm, and preferably, 0.001 to 1 μm.

Referring again to FIG. 2, an optional interlayer 216 may be disposedbetween the LTHC layer 214 and transfer layer 218. The interlayer can beused, for example, to minimize damage and contamination of thetransferred portion of the transfer layer and may also reduce distortionin the transferred portion of the transfer layer. The interlayer mayalso influence the adhesion of the transfer layer to the rest of thedonor sheet. Typically, the interlayer has high thermal resistance.Preferably, the interlayer does not distort or chemically decomposeunder the imaging conditions, particularly to an extent that renders thetransferred image non-functional. The interlayer typically remains incontact with the LTHC layer during the transfer process and is notsubstantially transferred with the transfer layer.

Suitable interlayers include, for example, polymer films, metal layers(e.g., vapor deposited metal layers), inorganic layers (e.g., sol-geldeposited layers and vapor deposited layers of inorganic oxides (e.g.,silica, titania, and other metal oxides)), and organic/inorganiccomposite layers. Organic materials suitable as interlayer materialsinclude both thermoset and thermoplastic materials. Suitable thermosetmaterials include resins that may be crosslinked by heat, radiation, orchemical treatment including, but not limited to, crosslinked orcrosslinkable polyacrylates, polymethacrylates, polyesters, epoxies, andpolyurethanes. The thermoset materials may be coated onto the LTHC layeras, for example, thermoplastic precursors and subsequently crosslinkedto form a crosslinked interlayer.

Suitable thermoplastic materials include, for example, polyacrylates,polymethacrylates, polystyrenes, polyurethanes, polysulfones,polyesters, and polyimides. These thermoplastic organic materials may beapplied via conventional coating techniques (for example, solventcoating, spray coating, or extrusion coating). Typically, the glasstransition temperature (T_(g)) of thermoplastic materials suitable foruse in the interlayer is 25° C. or greater, preferably 50° C. orgreater. In some embodiments, the interlayer includes a thermoplasticmaterial that has a T_(g) greater than any temperature attained in thetransfer layer during imaging. The interlayer may be eithertransmissive, absorbing, reflective, or some combination thereof, at theimaging radiation wavelength.

Inorganic materials suitable as interlayer materials include, forexample, metals, metal oxides, metal sulfides, and inorganic carboncoatings, including those materials that are highly transmissive orreflective at the imaging light wavelength. These materials may beapplied to the light-to-heat-conversion layer via conventionaltechniques (e.g., vacuum sputtering, vacuum evaporation, or plasma jetdeposition).

The interlayer may provide a number of benefits. The interlayer may be abarrier against the transfer of material from the light-to-heatconversion layer. It may also modulate the temperature attained in thetransfer layer so that thermally unstable materials can be transferred.For example, the interlayer can act as a thermal diffuser to control thetemperature at the interface between the interlayer and the transferlayer relative to the temperature attained in the LTHC layer. This mayimprove the quality (i.e., surface roughness, edge roughness, etc.) ofthe transferred layer. The presence of an interlayer may also result inimproved plastic memory in the transferred material.

The interlayer may contain additives, including, for example,photoinitiators, surfactants, pigments, plasticizers, and coating aids.The thickness of the interlayer may matrix or some other materials. Thereceptor substrate may be any item suitable for a particular applicationincluding, but not limited to, glass, transparent films, reflectivefilms, metals, semiconductors, and plastics. For example, receptorsubstrates may be any type of substrate or display element suitable fordisplay applications. Receptor substrates suitable for use in displayssuch as liquid crystal displays or emissive displays include rigid orflexible substrates that are substantially transmissive to visiblelight. Examples of suitable rigid receptors include glass and rigidplastic that are coated or patterned with indium tin oxide or arecircuitized with low temperature poly-silicon (LTPS) or other transistorstructures, including organic transistors.

Suitable flexible substrates include substantially clear andtransmissive polymer films, reflective films, transflective films,polarizing films, multilayer optical films, and the like. Flexiblesubstrates can also be coated or patterned with electrode materials ortransistors, for example transistor arrays formed directly on theflexible substrate or transferred to the flexible substrate after beingformed on a temporary carrier substrate. Suitable polymer substratesinclude polyester base (e.g., polyethylene terephthalate, polyethylenenaphthalate), polycarbonate resins, polyolefin resins, polyvinyl resins(e.g., polyvinyl chloride, polyvinylidene chloride, polyvinyl acetals,etc.), cellulose ester bases (e.g., cellulose triacetate, celluloseacetate), and other conventional polymeric films used as supports. Formaking OELs on plastic substrates, it is often desirable to include abarrier film or coating on one or both surfaces of the plastic substrateto protect the organic light emitting devices and their electrodes fromexposure to undesired levels of water, oxygen, and the like.

Receptor substrates can be pre-patterned with any one or more ofelectrodes, transistors, capacitors, insulator ribs, spacers, colorfilters, black matrix, hole transport layers, electron transport layers,and other elements useful for electronic displays or other devices.

The present invention contemplates polarized light emitting OEL displaysand devices. In one embodiment, OEL displays can be made that emit lightand that have adjacent devices that can emit light having differentcolor. For example, FIG. 3 shows an OEL display 300 that includes aplurality of OEL devices 310 disposed on a substrate 320. Adjacentdevices 310 can be made to emit different colors of light. depend onfactors such as, for example, the material of the interlayer, thematerial and properties of the LTHC layer, the material and propertiesof the transfer layer, the wavelength of the imaging radiation, and theduration of exposure of the donor sheet to imaging radiation. Forpolymer interlayers, the thickness of the interlayer typically is in therange of 0.05 μm to 10 μm. For inorganic interlayers (e.g., metal ormetal compound interlayers), the thickness of the interlayer typicallyis in the range of 0.005 μm to 10 μm.

Referring again to FIG. 2, a thermal transfer layer 218 is included indonor sheet 200. Transfer layer 218 can include any suitable material ormaterials, disposed in one or more layers, alone or in combination withother materials. Transfer layer 218 is capable of being selectivelytransferred as a unit or in portions by any suitable transfer mechanismwhen the donor element is exposed to direct heating or to imagingradiation that can be absorbed by light-to-heat converter material andconverted into heat.

The present invention contemplates a transfer layer that includes alight emitting, charge transporting, charge blocking, or semiconductingmaterial disposed in a non-polymeric, organic material that forms anamorphous matrix as part of the transfer layer. The present inventioncontemplates a transfer layer that includes a LEP or other lightemitting molecules as the light emitting material. One way of providingthe transfer layer is by solution coating the light emitting materialand non-polymeric, organic material onto the donor to form an amorphousmatrix containing the light emitting material. In this method, the lightemitting material and the non-polymeric, organic material can besolubilized by addition of a suitable compatible solvent, and coatedonto the alignment layer by spin-coating, gravure coating, mayer rodcoating, knife coating and the like. The solvent chosen preferably doesnot undesirably interact with (e.g., swell or dissolve) any of thealready existing layers in the donor sheet. The coating can then beannealed and the solvent evaporated to leave a transfer layer containingan amorphous matrix.

The transfer layer can then be selectively thermally transferred fromthe donor element to a proximately located receptor substrate. There canbe, if desired, more than one transfer layer so that a multilayerconstruction is transferred using a single donor sheet. The additionaltransfer layers can include an amorphous, non-polymeric, organic

The separation shown between devices 310 is for illustrative purposesonly. Adjacent devices may be separated, in contact, overlapping, etc.,or different combinations of these in more than one direction on thedisplay substrate. For example, a pattern of parallel stripedtransparent conductive anodes can be formed on the substrate followed bya striped pattern of a hole transport material and a striped repeatingpattern of red, green, and blue light emitting LEP layers, followed by astriped pattern of cathodes, the cathode stripes oriented perpendicularto the anode stripes. Such a construction may be suitable for formingpassive matrix displays. In other embodiments, transparent conductiveanode pads can be provided in a two-dimensional pattern on the substrateand associated with addressing electronics such as one or moretransistors, capacitors, etc., such as are suitable for making activematrix displays. Other layers, including the light emitting layer(s) canthen be coated or deposited as a single layer or can be patterned (e.g.,parallel stripes, two-dimensional pattern commensurate with the anodes,etc.) over the anodes or electronic devices. Any other suitableconstruction is also contemplated by the present invention.

In one embodiment, display 300 can be a multiple color display. As such,it may be desirable to position optional polarizer 330 between the lightemitting devices and a viewer, for example to enhance the contrast ofthe display. In exemplary embodiments, each of the devices 310 emitslight. There are many displays and devices constructions covered by thegeneral construction illustrated in FIG. 3. Some of those constructionsare discussed as follows.

OEL backlights can include emissive layers. Constructions can includebare or circuitized substrates, anodes, cathodes, hole transport layers,electron transport layers, hole injection layers, electron injectionlayers, emissive layers, color changing layers, and other layers andmaterials suitable in OEL devices. Constructions can also includepolarizers, diffusers, light guides, lenses, light control films,brightness enhancement films, and the like. Applications include whiteor single color large area single pixel lamps, for example where anemissive material is provided by thermal stamp transfer, laminationtransfer, resistive head thermal printing, or the like; white or singlecolor large area single electrode pair lamps that have a large number ofclosely spaced emissive layers patterned by laser induced thermaltransfer; and tunable color multiple electrode large area lamps.

Low resolution OEL displays can include emissive layers. Constructionscan include bare or circuitized substrates, anodes, cathodes, holetransport layers, electron transport layers, hole injection layers,electron injection layers, emissive layers, color changing layers, andother layers and materials suitable in OEL devices. Constructions canalso include polarizers, diffusers, light guides, lenses, light controlfilms, brightness enhancement films, and the like. Applications includegraphic indicator lamps (e.g., icons); segmented alphanumeric displays(e.g., appliance time indicators); small monochrome passive or activematrix displays; small monochrome passive or active matrix displays plusgraphic indicator lamps as part of an integrated display (e.g., cellphone displays); large area pixel display tiles (e.g., a plurality ofmodules, or tiles, each having a relatively small number of pixels),such as may be suitable for outdoor display used; and security displayapplications.

High resolution OEL displays can include emissive layers. Constructionscan include bare or circuitized substrates, anodes, cathodes, holetransport layers, electron transport layers, hole injection layers,electron injection layers, emissive layers, color changing layers, andother layers and materials suitable in OEL devices. Constructions canalso include polarizers, diffusers, light guides, lenses, light controlfilms, brightness enhancement films, and the like. Applications includeactive or passive matrix multicolor or full color displays; active orpassive matrix multicolor or full color displays plus segmented orgraphic indicator lamps (e.g., laser induced transfer of high resolutiondevices plus thermal hot stamp of icons on the same substrate); andsecurity display applications.

EXAMPLES Example 1 Preparation of a Receptors

Three different types of receptors were formed: (A) indium tin oxide(ITO) only; (B) PDOT (poly(3,4-ethylenedioxythiophene)) on ITO; and (C)mTDATA (4,4′,4″-tris(N-(3-methylphenyl)-N-phenylamino)triphenylamine) onPDOT/ITO. To obtain receptor surface (A), ITO glass (Delta Technologies,Stillwater, Minn., sheet resistance less than 100 Ω/square, 1.1 mmthick) was ultrasonically cleaned in a hot, 3% solution of Deconex 12NS(Borer Chemie AG, Zuchwil Switzerland). The substrates were then placedin the Plasma Science Model PS0500 plasma treater (4th State Inc.,Belmont, Calif.) for surface treatment under the following conditions:

Time: 2 minutes Power: 500 watt (165 W/cm²) Oxygen Flow: 100 sccm

To obtain receptor surface (B), the ITO was cleaned and plasma-treatedas described for the preparation of receptor surface (A). Immediatelyafter plasma treatment, the PDOT solution (CH-8000 from Bayer AG,Leverkusen, Germany, diluted 1:1 with deionized water) was filtered anddispensed through a Whatman Puradisc™ 0.45 μm Polypropylene (PP) syringefilter onto the ITO substrate. The substrate was then spun (HeadwayResearch spincoater) at 2000 rpm for 30 s yielding a PDOT film thicknessof 40 nm. All of the substrates were heated to 200° C. for 5 minutesunder nitrogen.

To obtain receptor surface (C), a PDOT film was deposited onto ITO asdescribed for the preparation of receptor surface (B). After thesubstrates had cooled, a solution of mTDATA (OSA 3939, H. W. SandsCorp., Jupiter, Fla.) 2.5% (w/w) in toluene was filtered and dispensedthrough a Whatman Puradisc™ 0.45 μm Polypropylene (PP) syringe filteronto the PDOT coated ITO substrate. The substrate was spun (HeadwayResearch spincoater) at 3000 rpm for 30 s yielding an mTDATA filmthickness of 40 nm.

Example 2 Preparation of a Donor Sheet Without Transfer Layer

A thermal transfer donor sheet was prepared in the following manner.

An LTHC solution, given in Table I, was coated onto a 0.1 mm thickpolyethylene terapthalate (PET) film substrate from Teijin (Osaka,Japan). Coating was performed using a Yasui Seiki Lab Coater, ModelCAG-150, using a microgravure roll with 150 helical cells per linealinch. The LTHC coating was in-line dried at 80° C. and cured underultraviolet (UV) radiation.

TABLE I LTHC Coating Solution Trade Parts Component Designation byWeight carbon black pigment Raven 760 Ultra⁽¹⁾ 3.55 polyvinyl butyralresin Butvar B-98⁽²⁾ 0.63 acrylic resin Joncryl 67⁽³⁾ 1.90 dispersantDisperbyk 161⁽⁴⁾ 0.32 surfactant FC-430⁽⁵⁾ 0.01 epoxy novolac acrylateEbecryl 629⁽⁶⁾ 12.09 acrylic resin Elvacite 2669⁽⁷⁾ 8.062-benzyl-2-(dimethylamino)-1-(4- Irgacure 369⁽⁸⁾ 0.82 (morpholinyl)phenyl) butanone 1-hydroxycyclohexyl phenyl ketone Irgacure 184⁽⁸⁾ 0.122-butanone 45.31 1,2-propanediol monomethyl ether 27.19 acetate⁽¹⁾available from Columbian Chemicals Co., Atlanta, GA ⁽²⁾available fromSolutia Inc., St. Louis, MO ⁽³⁾available from S. C. Johnson & Son, Inc.,Racine, WI ⁽⁴⁾available from Byk-Chemie USA, Wallingford, CT⁽⁵⁾available from Minnesota Mining and Manufacturing Co., St. Paul, MN⁽⁶⁾available from UCB Radcure Inc., N. Augusta, SC ⁽⁷⁾available from ICIAcrylics Inc., Memphis, TN ⁽⁸⁾available from Ciba-Geigy Corp.,Tarrytown, NY

Next, an interlayer, given in Table II, was coated onto the cured LTHClayer by a rotogravure coating method using the Yasui Seiki Lab Coater,Model CAG-150, with a microgravure roll having 180 helical cells perlineal inch. This coating was in-line dried at 60° C. and UV cured.

TABLE II Interlayer Coating Solution Component Parts by Weight SR 351 HP(trimethylolpropane triacrylate 14.85 ester, available from Sartomer,Exton, PA) Butvar B-98 0.93 Joncryl 67 2.78 Irgacure 369 1.25 Irgacure184 0.19 2-butanone 48.00 1-methoxy-2-propanol 32.00

Example 3 Preparation of Solutions for Transfer Layer

The following solutions were prepared:

(a) Covion green. Covion Green PPV Polymer HB 1270 (100 mg) from CovionOrganic Semiconductors GmbH, Frankfurt, Germany was weighed out into anamber vial with a PTFE cap. To this was added 9.9 g of Toluene (HPLCgrade obtained from Aldrich Chemical, Milwaukee, Wis.). The vialcontaining the solution was placed into a silicone oil bath at 75° C.for 60 minutes. The hot solution was filtered through a 0.45 μmPolypropylene (PP) syringe filter.

(b) Covion super yellow. Covion PDY 132 “Super Yellow” (75 mg) wasweighed out into an amber vial with a PTFE cap. To this was added 9.925g of Toluene (HPLC grade obtained from Aldrich Chemicals) and a stirbar. The solution was stirred overnight. The solution was filteredthrough a 5 μm Millipore Millex syringe filter.

(c) mTDATA. Into a container was weighed out 100 mg mTDATA (OSA 3939available from H. W. Sands Corp, Jupiter, Fla.). To this was added 3.9 gof Toluene (HPLC grade obtained from Aldrich Chemical; Milwaukee, Wis.).The solution was heated at 75° C. while stirring in silicone oil bathfor 25 minutes. The hot solution was filtered through a WhatmanPuradisc™ 0.45 μm Polypropylene (PP) filter.

(d) t-Butyl PBD. Into a container was weighted out 100 mg t-butyl PBD(2-(biphenyl-4-yl)-5-(4-(1,1-dimethylethyl)phenyl)-1,3,4-oxadiazole,available from Aldrich Chemical Co., Milwaukee, Wis.). To this was added3.9 g of Toluene (HPLC grade obtained from Aldrich Chemicals). Thesolution was stirred for 25 minutes and filtered through a WhatmanPuradisc™ 0.45 μm Polypropylene (PP) filter.

Examples 4-8 Preparation of Transfer Layers on Donor Sheet and Transferof Transfer Layers

Transfer Layers were formed on the donor sheets of Example 2 usingblends of the Solutions of Example 3 according to Table III. To obtainthe blends, the above described solutions were mixed at the appropriateratios and the resulting blend solutions were stirred for 20 min at roomtemperature.

The transfer layers were disposed on the donor sheets by spinning(Headway Research spincoater) at about 2000 rpm for 30 s to yield a filmthickness of approximately 100 nm.

TABLE III Parts by Weight of Transfer Layer Compositions Covion SuperExample No. Covion Green Yellow mTDATA t-butyl PBD 4 1 — — 2 5 2 — — 5 61 — — 3 7 1 — 1 1 8 — 1 3 —

Donor sheets as prepared in Examples 4-8 were brought into contact withreceptor substrates as prepared in Example 1. Next, the donors wereimaged using two single-mode Nd:YAG lasers. Scanning was performed usinga system of linear galvanometers, with the combined laser beams focusedonto the image plane using an f-theta scan lens as part of anear-telecentric configuration. The laser energy density was 0.4 to 0.8J/cm². The laser spot size, measured at the 1/e² intensity, was 30micrometers by 350 micrometers. The linear laser spot velocity wasadjustable between 10 and 30 meters per second, measured at the imageplane. The laser spot was dithered perpendicular to the majordisplacement direction with about a 100 μm amplitude. The transferlayers were transferred as lines onto the receptor substrates, and theintended width of the lines was about 100 μm.

The transfer layers were transferred in a series of lines that were inoverlying registry with the ITO stripes on the receptor substrates. Theresults of imaging are given in Table IV.

TABLE IV Results of Transfer Example Substrate (A) Substrate (B)Substrate (C) No. ITO ITO/PDOT ITO/PDOT/mTDATA 4 excellent transfer;spotty transfer, no excellent transfer; excellent edge continuous linesgood edge quality quality 5 excellent transfer; spotty transfer, noexcellent transfer; excellent edge continuous lines good edge qualityquality 6 excellent transfer; spotty transfer, no excellent transfer;excellent edge continuous lines good edge quality quality 7 excellenttransfer; good transfer; excellent transfer; excellent edge good edgequality excellent edge quality quality 8 excellent transfer goodtransfer with excellent transfer; at high laser dose; some holeexcellent edge quality excellent edge defects; excellent quality at highedge quality laser dose

Example 9 Preparation of OEL Devices

The three transfer layer compositions of Examples 4-6 were used toprepare light-emitting diodes of the constructionITO/PDOT/mTDATA/Transfer Layer/Ca/Ag. After transfer of the transferlayer as described in Examples 4-6, Ca/Ag cathodes were vapor depositedusing the following conditions:

Thickness Rate Coating time Ca  400 A 1.1 A/s  5 min 51 s Ag 4000 A 5.0A/s 13 min 20 sIn all cases diode behavior and green light emission were observed.

The present invention should not be considered limited to the particularexamples described above, but rather should be understood to cover allaspects of the invention as fairly set out in the attached claims.Various modifications, equivalent processes, as well as numerousstructures to which the present invention may be applicable will bereadily apparent to those of skill in the art to which the presentinvention is directed upon review of the instant specification.

Each of the patents, patent documents, and publications cited above ishereby incorporated into this document as if reproduced in full.

1. A method of making an organic electroluminescent display or device,the method comprising: providing a donor sheet comprising a substrateand a transfer layer disposed on the substrate, the transfer layercomprising an amorphous, non-polymeric, organic light-emitting dendrimerand an electrically active material; providing a receptor; and thermallytransferring at least a portion of the transfer layer to the receptor.2. The method of claim 1, wherein the donor sheet further comprises alight-to-heat conversion layer disposed between the substrate and thetransfer layer.
 3. The method of claim 2, wherein the donor sheetfurther comprises an interlayer disposed between the light-to-heatconversion layer and the transfer layer.
 4. The method of the claim 2,wherein the donor sheet further comprises an underlayer disposed betweenthe substrate and the light-to-heat conversion layer.
 5. The method ofclaim 1, wherein the transfer layer comprises more than one layer. 6.The method of claim 1, wherein the transfer layer is solution coated onthe substrate.
 7. The method of claim 1, wherein the donor sheet isdirectly heated to thermally transfer at least a portion of the transferlayer to the receptor.
 8. The method of claim 1, wherein the donor sheetis exposed to imaging radiation that is converted into heat to thermallytransfer at least a portion of the transfer layer to the receptor. 9.The method of claim 8, wherein the donor sheet further comprises alight-to-heat conversion layer that converts the imaging radiation intoheat.
 10. The method of claim 9, wherein the donor sheet is exposed toimaging radiation through a mask.
 11. The method of claim 9, wherein thedonor sheet is exposed to imaging radiation generated by a laser. 12.The method of claim 8, wherein the donor sheet and the receptor arebrought into intimate contact during thermal transfer of at least aportion of the transfer layer to the receptor.
 13. The method of claim8, wherein the donor sheet is spaced from the receptor during thermaltransfer of at least a portion of the transfer layer to the receptor.14. The method of claim 8, wherein at least a portion of the transferlayer is thermally transferred to the receptor in an imagewise fashionto form a pattern on the receptor.
 15. The method of claim 1, whereinthe electrically active material produces, conducts or semi-conducts acharge carrier.
 16. The method of claim 1, wherein the electricallyactive material comprises a hole transport material.
 17. The method ofclaim 1, wherein the electrically active material comprises an electrontransport material.